Junction between single and pushpull lines



Feb. 11, 1941. N. E. LINDENBLAD JUNCTION BETWEEN SINGLE AND PUSH-PULL LINES Filed May 27, 1939 2 Sheets-Sheet 2 I N VEN TOR. N/LS E. L/NDENBLAD A TTORN E Y.

pained Feb. 11, 19417 2,231.839

UNITED STATES PAII'IEZPJ'T ()FFICE JUNCTION BETWEEN SINGLE AND PUSH- PULL LINES I Nils E. Lindenblad, Rocky Point, N. Y., assignor to Radio Corporation of America, a corporation of Delaware Application May 27, 1939, Serial No. 276,193 I 13 Claims. (01.178-44) The present invention'relates to transmission grounded. I have also shown a pair of lines lines and, more particularly, to a means for couadapted to be fed in a push-pull relationship, pling a single line to a push-pull line or a pair one of said lines being composed of an outer of transmission lines operating in a push-pull sheath 8 and an inner conductor 9, and the other a relationship. being composed of an outer sheath ii] and an 5 An object of the present invention is to proinner conductor I I. The inner conductor 9 is vide a junction between a single and a pushdirectly connected to inner conductor 1 and is, pull line. therefore, energized in the same relationship as Another object of the present invention is to the conductor 1. The other inner conductor II N provide a transformer for coupling a singleline is directly connected to the end of the sheath to a push-pull line which will not unbalance 6 of the single line and is therefore energized in either the single line or the push-pull line. phase opposition to the inner conductor 9. In

Still a further object of the present invention order to completely uncouple the last quarter is to provide a transformer for coupling from a wave section of the single transmission line 6, 1

single to a push-pull line which maintains perfrom the remainder of the same, I have provided feet balance over a wide frequency band. an outer shell 12 surrounding sheath 6 of the Still a further object of the present invention single transmission line and connected thereto is to provide a transformer for coupling from at a distance equal to a quarter of the operating a single to a push-pull line which maintains Wave length from the point of connection of con- "6 perfect balance over a wide frequency band, or ductor H. The length of the conducting path vice-versa. Within outer shell l2 and including the outer My invention involves the connection of one surface of the sheath 6 is of such length that of a pair of push-pull lines to one conductor of the point of connection of conductor II is eleca single line and the other of the push-pull lines trically freed from the outer conductor of the to the other conductor of the single line with transmission line as far as ground potentials are 25 means interposed between the push-pull lines concerned. This effect is due to the fact that and the single line for preventing any unthe length of the conducting path discussed balancing effect upon the push-pull line from presents an extremely high impedance to the the connections of the single line. operating frequency of the apparatus at the My invention further contemplates the propoint of attachment of conductor ll. Further- 30 vision of means for counterbalancing any remore, no radiation can take place from the ouractive components in the lines due to; the conrent flowing along the outer surface of sheath 6 nection between the single and push-pull lines. since the current flowing along the inside of the Further objects and features of my invention outer shell I2 is equal and of opposite direction.

Will be readily apparent from the following de- Thus it will be seen that at the frequency for 35 tailed description which is accompanied by drawwhich the junction is designed the balanced ings in which Figure 1 illustrates an embodiment push-pull line will not be subject to any unof the present invention; Figure 2 illustrates a balancin effects fIOm t C t s o he modification of the form of my invention shown single lines, etc. This condition is, however, true in Figure 1 in which certain reactive components only when the surrounded section of the single 40 are added for balance; Figure 3 illustrates still transmission line pp xi t s a q r f h a further modification in which the reactive length of e Operating Wave in length- I the components are substantially completely comfrequency s changed or if the operating f pensated for; Figure 4illustrates afurther modiquency is Widely modulated some current will fication of my invention in which the reactive leak over the edge of the single transmission 45 component due to the coupling between the single line Sheath 6 a the p -p Output Circuit and push pu11 line is prevented from affecting will be unbalanced. In order to maintain perfect the single line, while Figure 5 illustrates a modibalance ov a v ry W f q n y d I utilize fication of Figure 4 particularly adapted to feed the modification shown in Fi e 2 in Which I so four transmission lines in a successive phase l y a second q a w conductor iii quadrature arrangement. ranged in an end-0n relationship with the single f rin n t Figure 1 I h v h wn a line sheath 6 and surrounded by an outer shell 22. single concentric cable or transmission line com- The center conductor 26, having the Same diameposed of an outer sheath 6 and a central inner ter as the outer diameter of the sheath 6 of the 5:3 conductor 1. The outer sheath ma be single transmission line, is connected at one end to the center conductor I of the single line and also to the center conductor 9 of one of the pushpull lines. The other end is electrically connected to the end of shell 22. With this construction it will be seen that looking from the push-pull line toward the junction along either conductor 9 or conductor H an exactly similar set of conditions is encountered. Therefore, for a wide frequency band or for frequencies varying widely from the frequency for which the junction is designed the reactive drain on conductor H due to an improper length of the surrounded portion of sheath 6 of the single transmission line is duplicated by an equal drain on conductor 9 by conductor 26. Since both lines 9 and I l are connected through conductors 6, 26 to conductors 1, 6 of the single line, the current delivered by the single line results in perfectly balanced currents in the push-pull lines. Although the push-pull output remains balanced over a wide band of frequencies there is a reactive component produced causing reflection toward the source and the magnitude of this increases as the frequency departs from the frequency for which the junction was designed. It should be noted that this reflection takes place regardless of whether the energy feeds from push-pull to single line, or vice-versa.

In order to compensate for this effect I may use the modification of my invention shown in Figure 3. The construction of the left-hand portion of Figure 3 is exactly the same as described with reference to Figure 2. However, in each of the push-pull lines 8 and It at a distance equal to a quarter of the length of the operating wave from the junction I have provided balancing reactances. The theory of operation by which one insulator may compensate for the rectance introduced by an exactly similar one spaced therefrom a quarter wavelength has been discussed in some detail in a prior application by P. S. Carter, No. 112,037, filed November 21, 1936, and assigned to the assignee of the present application. The present invention applies a similar reasoning to the compensation of reactance introduced in a transmission line junction. The compensating reactance in line 8 is composed of outer shell 32 and center conductor 35. Center conductor 36 is connected at one end to conductor 9 and at the other end to shell 32. These elements are of the same physical dimensions as shell 22 and center conductor 26. Since all the physical dimensions are the same the reactances and resistance of both sections will be exactly the same and due to the quarter wave spacing each will compensate equally well for the other on each side of the midfrequency. For exact compensation at any particular side frequency the spacing will differ correspondingly from a quarter wave. Likewise, in line H! of the balanced push-pull line I have provided a similar balancing reactance composed of outer shell 32 and center conductor 36' and connected in the same way as heretofore described.

While I have shown the outer shell 32 and 32' as being one continuous structure it is within the field of the present invention to make them entirely separate, if desired. However, from the standpoint of mechanical construction it is more desirable to make the two shell portions integral.

In Figure 4 I have shown a modification of the form of my invention shown in Figure 3 which is designed to supply a pair of lines in a phase quadrature relationship. This particular phase relationship is desirable, for example, when energizing a turnstile antenna. This phase relationship is very simply provided for by including in transmission line 10 a phasing loop Ml having a length equal to a quarter of the length of the operating wave. This additional quarter wave length of the transmission line serves to delay the wave along the line an additional electrical degrees, as clearly shown in Figure 4. Furthermore, in order to more completely counterbalance reactances, instead of having the single transmission line B, 1 connected to the double line within shell I2, I have divided the single line into two branches, one of which is connected within outer shell l2 as before. The other branch 35" having an inner conductor 31' is substituted for the conductor 36' shown in Figure 3. It will be seen by following the connections from the junction of transmission line 6, 1 and connection 36", 31 around through the loop that each joint or connection is compensated by an exactly similar connection a quarter of the length of the operating wave away.

In Figure 5 I have shown a further development of the modification shown in Figure 4 which is particularly adapted to feed all four phases of a phase quadrature turnstile antenna. The structure for machine from a single to a pushpull line is the same as in previous figures, so it has not here been shown in detail. Each of the push-pull transmission lines 8 and H] are arranged to energize two arms of a turnstile antenna by means of a pair of connections spaced a quarter of the length of the operating wave apart thus obtaining the phase quadrature relationship. For instance, connected to conductor 8 is a final transmission line 5! and at a distance a quarter of the length of the operating wave away a second line 54. Likewise, to transmission line H) are connected transmission lines 52 and 53 spaced a quarter of the length of the operating wave apart. The resultant phase relationship of the four transmission lines is shown in the figure and should be obvious without further explanation. If similar radiating members are connected to each of the lines 5|, 52, 53, 54, for any reflection back into line 8 from line 5| there is a similar reflection from line 54. The spacing between these lines being a quarter of the length of the operating Wave, each reflection compensates for the other and there is very little final resultant effect in line 8. A similar situation, of course, likewise exists with respect to lines 52 and 53 and their connection to transmission line I0. Throughout the present application where I refer to the operating frequency with respect to a Wide band system it is to be understood that the midband frequency is considered.

While I have particularly shown and described several modifications of my invention, it is to be distinctly understood that my invention is not limited thereto but that improvements within the scope of the invention may be made.

I claim:

1. In combination, a single transmission line having an outer sheath and an inner conductor and a push-pull pair of balanced transmission lines, a connection from the inner conductor of said single line to a conductor of one of said push-pull lines, a connection from the sheath of said single line to a conductor of the other of said push-pull lines, an outer shell surrounding the end portion of said single line, said shell being connected to said sheath at a distance equal to a quarter of the length of the operating wave from the end of said single line, and a balancing circuit including an inner conductor connected to the inner conductor of said single line and having a diameter equal to the diameter of the outer sheath of said single line and an outer shell'having a diameter equal to the diameter of the first outer shell and connected thereto, the inner conductor and outer shell of said balancing circuit being connected together at a distance equal to a quarter of the length of the operating wave from said connections.

2. In combination, a single transmission line having an outer sheath and an inner conductor and a pair of balanced transmission lines, a connection from the inner conductor of said single line to a conductor of one of said pair of lines, a connection from the sheath of said single line to a conductor of the other of said pair of lines, an outer shell surrounding the endportion of said single line, said shell being connected to said sheath at a distance equal to a quarter of the length of the operating wave from the end of said single line, a balancing circuit including an inner conductor connected to the inner conductor of said single line and having a diameter equal to the diameter of the outer sheath of said single line and an outer shell having a diameter equal to the diameter of the first outer shell and connected thereto, the inner conductor and outer.

shell of said balancing circuit being connected together at a distance equal to a quarter of the length of the operating wave from said connections, and a compensating circuit similar to said balancing circuit connected to each of said pair of lines at a distance equal to a quarter of the length of the operating wave from said junction whereby the reactance of said junction is compensated.

3. Means for coupling a single concentric line having an outer sheath and an inner conductor to a push-pull pair of concentric transmission lines each having an outer sheath and an inner conductor comprising a connection from the inner conductor of said single line to an inner conductor of one of said pair of lines, a connection from the end of the sheath of said single line to the inner conductor of the other of said pair of lines, an outer shell surrounding the end of said single lines and its junction with said pair of lines, said shell being connected to the outer sheath of said single line at a distance equal to a quarter of the length of the operating wave from the end of said sheath, and a balancing circuit including an inner conductor having a diameter equal to the diameter of the outer sheath of said single line connected to the inner conductor of said single line and an outer shell having a diameter equal to the diameter of said first outer shell and connected thereto, the inner conductor and outer shell of said balancing circuit being connected together at a distance equal to a quarter of the length of the operating wave from said connections.

4. Means for coupling a single concentric line having an outer sheath and an inner conductor to a push-pull pair of concentric transmission lines each having an outer sheath and an inner conductor comprising a connection from the inner conductor of said single line to an inner conductor of one of said pair of lines, a connection from the end of the sheath of said single line to the inner conductor of the other of said pair of lines, an outer shell surrounding the end of said single lines and its junction with said pair of lines, said shell being connected to the outer sheath of said single line at a distance equal to a quarter of the length of the operating wave from the end of said sheath, and a balancing circuit including an inner conductor having a diameter equal to the diameter of the outer sheath of said single line connected to the inner conductor of said single line and an outer shell having a diameter equal to the diameter of said first outer shell and connected thereto, the inner conductor and outer shell of said balancing circuit being connected together at a distance equal to a quarter of the length of the operating wave from said connections, and a compensating circuit similar to said balancing circuit connected to each of said pair of push-pull lines at a distance equal to a quarter of the length of the operating wave from said junction whereby the reactance of said junction is compensated.

5. Means for coupling a single concentric line having an outer sheath and an inner conductor to a push-pull circuit having a pair of conductors adapted to be energized in an opposing phase relationship comprising a connection from said inner conductor to one of said pair of conductors, a connection from the end of said outer sheath to the other of said pair of conductors and an outer shell surrounding the end of said single line and its junction with said pair of lines, said shell-being connected to said outer sheath at a distance equal to a quarter of the length of the operating Wave from the end of said sheath, and a balancing circuit including an inner conductor having a diameter equal to the diameter of the outer sheath of said single line connected to the inner conductor of said single line and an outer shell having a diameter equal to the diameter of said first outer shell and connected thereto, the inner conductor and outer shell of said balancing circuit being connected together at a distance equal to a quarter of the length of the operating wave from said connections.

6. Means for coupling a single concentric transmission line having an outer sheath and an inner conductor to a push-pull pair of concentric transmission lines each having an outer sheath and an inner conductor, said single line being branched into two branches, one of said branches being a quarter of the length of the operating wave longer than the other of said branches, said means comprising a connection from the inner conductor of one of said pair of lines to each of the inner conductors of said branches, a connection from the inner conductor of the other of said pair of lines to the end of the outer sheath of each of said branches, an outer shell surrounding the end of each branch of said single line, said shells being connected to the outer sheath and said branches at a distance equal to a quarter of the length of the operating Wave from the end of each branch, said outer shell extending beyond the ends of said branches, and an inner conductor within the extending portion of said shells having a diameter equal to the diameter of the outer sheath of said single line connected to the inner conductors of said branches, each of said outer shells. and said last mentioned inner conductors being connected together a distance equal to a quarter of the length of the operating wave beyond the point of connection to said inner conductors.

7. Means for coupling a single concentric line having an outer sheath and an inner conductor to a push-pull pair of concentric transmission lines each having an outer sheath and an inner conductor comprising a connection from the inner conductor of said single line to an inner conductor of one of said pair of lines, a connection from the end of the sheath of said single line to the inner conductor of the other of said pair of lines, an outer shell surrounding the end of said single lines and its junction with said pair of lines, said shell being connected to the outer sheath of said single line at a distance equal to a quarter of the length of the operating wave from the end of said sheath, and a balancing circuit including an inner conductor having a diameter equal to the diameter of the outer sheath of said single line connected tothe inner conductor of said single line and an outer shell having a diameter equal to the diameter of said first outer shell and connected thereto, the inner conductor and outer shell of said balancing circuit being connected together at a distance equal to a quarter of the length of the operating wave from said connections, and a compensating circuit having an impedance equal to that of said balancing circuit connected to each of said pair of push-pull lines at a distance equal to a quarter of the length of the operating Wave from said junction whereby the reactance of said junction is compensated.

8. Means for coupling a single concentric line having an outer sheath and an inner conductor to a push-pull circuit having a pair of conductors adapted to be energized in an opposing phase relationship comprising a connection from said inner conductor to one of said pair of conductors, a connection from the end of said outer sheath to the other of said pair of conductors and an outer shell surrounding the end of said single line, said shell being connected to said outer sheath at a distance equal to a quarter of the length of the operating wave from the end of said sheath, and a balancing circuit including an inner conductor having a diameter equal to the diameter of the outer sheath of said single line connected to the inner conductor of said single line and an outer shell having a diameter equal to the diameter of said first outer shell and connected thereto, the inner conductor and outer shell of said balancing circuit being connected together at a distance equal to a quarter of the length of the operating wave from said connections.

9. A concentric transmission line circuit comprising a single concentric transmission line having an outer sheath and an inner conductor to a push-pull pair of concentric transmission lines each having an outer sheath and inner conductor, said inner conductor being branched into two branches, one of said branches being a quarter of the length of the operating wave longer than the other of said branches, a connection from the inner conductor of one of said pair of lines to each of the inner conductors of said branches,'a connection from the inner conductor of the other of said pair of lines to the end of the outer sheath of each of said branches, an outer shell surrounding the end of each branch of said single line, said shell being connected to the outer sheath of said branches at a distance equal to a quarter of the length of the operating wave from the end of each branch, said outer shell extending beyond the ends of said branches, and the inner conductor having a diameter equal to the diameter of the outer sheath of said single line connected to the inner conductors of said branches, each of said outer shells and said last mentioned inner conductors being connected together a distance equal to a quarter of the length of the operating wave beyond the point of connection to said inner conductors, each of said push-pull pair of lines being divided into two branches, one branch of each being a quarter of the length of the operating wave longer than the other, whereby four phase output is obtained.

10. Means for coupling over a wide band of frequencies a single concentric line having an outer sheath and an inner conductor to a push-pull circuit having a pair of conductors adapted to be energized in an opposing phase relationship comprising a connection from said inner conductor to one of said pair of conductors, a connection from the end of said outer sheath to the other of said pair of conductors and an outer shell surrounding the end of said single line, said shell being connected .to said outer sheath at a distance from the end of said sheath equal to a quarter wavelength at midband frequency, the surrounded portion of said outer sheath introducing at frequencies removed from said midband an undesired reactive effect into one of said pair of conductors and an exactly similar reactance connected .to the end of the other of said pair of conductors whereby said push-pull circuit remains balanced over said Wide band.

11. Means for coupling over a Wide band of frequencies a single concentric line having an outer sheath and an inner conductor to a push-pull circuit having a pair of conductors adapted to be energized in an opposing phase relationship comprising a connection from said inner conductor to one of said pair of conductors, a connection from the end of said outer sheath to the other of said pair of conductors and an outer shell surrounding the end of said single line, said shell being connected to said outer sheath at a distance from the end of said sheath equal to a quarter wavelength at midband frequency, the surrounded portion of said outer sheath introducing at frequencies removed from said midband an undesired reactive efiect into one of said pair of conductors and an exactly similar reactance connected to said other one of said pair of conductors at a quarter wavelength distance from its end.

12. Means for coupling over a Wide band of frequencies a single concentric line having an outer sheath and an inner conductor to a push-pull circuit having a pair of conductors adapted to be energized in an opposing phase relationship comprising a connection from said inner conductor to one of said pair of conductors, a connection from the end of said outer sheath to the other of said pair of conductors and an outer shell surrounding the end of said single line, said shell being connected to said outer sheath at a distance from the end of said sheath equal to a quarter wavelength at midband frequency, the surrounded portion of said outer sheath introducing at frequencies removed from said midband an undesired reactive efiect into one of said pair of conductors, an exactly similar reactance connected to the end of the other of said pair of conductors to compensate for said reactive effect and further similar reactances connected to each of said pair of con ductors at a quarter wavelength distance from their ends, each of said reactances comprising a quarter Wave section of transmission line.

13. Means for coupling over a wide band of frequencies a single concentric line having an outer sheath and an inner conductor to a push-pull circuit having a pair of conductors adapted to be energized in an opposing phase relationship comprising a connection from said inner conductor to one of said pair of conductors, a connection from the end of said outer sheath .to the other of said pair of conductors and an outer shell surrounding the end of said single line, said shell being connected to said outer sheath at a distance from the end of said sheath equal to a quarter wavelength at midband frequency, the surrounded portion of said outer sheath introducing-at frequencies removed from said midband an undesired reactive efiect into one of said pair of conductors, an exactly similar reactance connected to the end of the other of said pair of conductors to compensate for said reactive efiect and further similar reactances connected to each of said pair of conductors at a quarter wavelength distance from their ends, each of said reactances comprising a quarter wave section of transmission line, said sections of transmission line being shorted at the ends remote from their connections to said pair of conductors.

NILS E. LINDENBLAD. 

